a. Field of the Invention
The present invention relates to laser scanning beam deflectors, and particularly, to a means and method for linearization of the scan velocity of resonant vibrating-mirror beam deflectors.
b. Problems in the Art
The development and utilization of laser scanning systems and apparatus have rapidly expanded, and continue to expand. Applications are diverse, for example such systems can be used in grocery store checkout lines and in highly sophisticated spacial imaging. Other examples are laser light shows, displays, information storage and retrieval, and high-quality printers.
A variety of different types of scanning systems have been developed. Most of them utilize some type of beam deflector to facilitate scanning of the beam. In turn, there are a variety of different types of analog or continuously variable beam deflectors which can be utilized. Five major types of analog beam deflectors are (1) electro-optical, (2) acousto-optical, (3) galvanometers, (4) polygon scanners, and (5) resonant vibrating mirrors. These types of analog beam deflectors are well known within the art.
Each of the above-mentioned types of analog beam deflectors has certain strengths and weaknesses. For deflection efficiency, reproducibility, and large angular scan range, the mechanical type deflectors are generally preferred.
As is known in the art, and as can be appreciated, mechanical deflectors deflect the scanning beam to cause an angular and varying reflection to achieve side-to-side scanning of the beam. As can be further appreciated, it is many times advantageous to have the beams scan continuously at a linear scanning velocity.
Some mechanical deflectors, such as the polygon scanners, can obtain a linear scan velocity over only a small angle at the focal plane. Resonant vibrating mirror deflectors, having a sine-like angular velocity, have linear scanning velocity deficiencies.
Presently, most attempts to obtain linear scanning velocity for resonant vibrating mirror deflectors consist of complicated timing circuits for the scanned data. This manipulation of the data is done after retrieval and requires costly equipment.
Additionally, there are certain applications where true linear scanning velocity is needed for accurate and valid results. One example is spatial imaging where integrated intensity must be constant over the scan region.
It is therefore a principal object of the present invention to provide a linearization of scan velocity of resonant vibrating-mirror beam deflectors which improves over or solves deficiencies and problems in the art.
It is another object of the present invention to eliminate the need for complicated and costly electronic timing circuitry to attempt to approximate linearization scan velocities into the acquired data.
A further object of the present invention is to provide a simple, inexpensive improvement to linearizing scan velocity which can be reliable and accurately used for a variety of applications.
A further object of the present invention is to provide true linearization of scan velocity during the scanning.
Another object of the present invention is to provide acceptable deflection efficiency, reproducibility, and angular scan range.
Another object of the present invention is to allow application of the scanning system to a variety of different uses, with conventional resonant beam deflector scanning apparatus.
Further object of the present invention is to provide essentially constant linear scanning velocity with minimal variation across the entire scanning range.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.